Bart's troublemaking claims the life of a bird, and in repentance, he decides to take care of the eggs in its nest -- until he learns that the abandoned baby birds are actually reptilian pests who feed off birds.
--> "You even compensated for the crooked sight!"
* InMemoriam: This episode is dedicated to PhilHartman, who makes his final Simpsons appearance as Troy [=McClure=] in this episode.
* RunningGag: Homer falling downstairs into the unlit basement.
* SummonBiggerFish: Done 4 times in a row. After Bart releases the lizards to prevent them from being killed, Skinner warns him he has no idea what he has unleashed...and later changes his tune because the lizards wiped out the pigeon population, which the town considered a plague.
-->'''Skinner:''' Well, I was wrong. The lizards are a godsend.
-->'''Lisa:''' But isn't that a bit short-sighted? What happens when we're overrun by lizards?
-->'''Skinner:''' No problem. We simply unleash wave after wave of Chinese needle snakes. They'll wipe out the lizards.
-->'''Lisa:''' But aren't the snakes even worse?
-->'''Skinner:''' Yes, but we're prepared for that. We've lined up a fabulous type of gorilla that thrives on snake meat.
-->'''Lisa:''' But then we're stuck with gorillas!
-->'''Skinner:'''No, that's the beautiful part. When wintertime rolls around, the gorillas simply freeze to death.
* YourApprovalFillsMeWithShame: Nelson inflicts this on Bart.